Aburaki et al. U.S. Pat. No. 4,406,899 discloses 7-[.alpha.-(2-aminothiazol-4-yl)-.alpha.-(Z)-methoxyiminoacetamido]-3-[(1m ethyl-1-pyrrolidinio)-methyl]-3-cephem-4-carboxylate in the zwitterion form and mentions corresponding acid addition salts and shows that the zwitterion form has broader spectrum activity than ceftazidime and cefotaxime. It refers to the zwitterion as 7-[(Z)-2-methoxyimino-2-(2-aminothiazol-4-yl)acetamido]-3-[(1-methyl-1-pyr rolidinium)methyl]-3-cephem-4-carboxylate.
Kessler et al., "Comparison of a New Cephalosporin, BMY-28142, with Other Broad-Spectrum .beta.-Lactam Antibiotics", Antimicrobial Agents and Chemotherapy, Vol. 27, No. 2, pp. 207-216, February 1985 mentions the sulfate salt.
Kaplan et al. U.S. Ser. No. 762,235, filed August 5, 1985 discloses various acid addition salts.
The zwitterion and its acid addition salts are stable for approximately 8-16 hours as injectable compositions in aqueous solution at 24.degree. C. The zwitterion even as a dry powder is unstable at room temperature and loses 30% or more of its activity on storage at elevated temperatures (e.g. 45.degree. C. and above) for even one week and must be stored at -30.degree. C. for adequate stability and therefore cannot be considered as appropriate for use under normal refrigeration conditions, i.e. those conditions available at pharmacies.
The aforementioned acid addition salts while possessing better temperature stability in the dry powder form than the zwitterion are too acidic for intramuscular and intravenous use and must be formulated with bases and/or buffering agents at pH 3.5-6.5 for such use.